Explanation:
Could life once have survived on Mars?
Today, neither
animal nor
plant life from
Earth could survive for very long on
Mars because at least one key ingredient -- liquid
water -- is essentially absent on the red planet's rusty surface.
Although evidence from the
martian rovers indicates that long ago
Mars might once have had
liquid water on its surface, that water might also have been
too acidic for familiar life forms to thrive.
Recently, however, a newly detailed analysis of an unusual outcropping of rock and soil chanced upon in 2005 by the robotic
Spirit rover has uncovered a clue indicating that not all of Mars was always so acidic.
The mound in question, dubbed
Comanche Outcrop and visible near the top of the
above image, appears to contain unusually
high concentrations of elements such as magnesium iron
carbonate.
The above image is shown in colors exaggerated to highlight the differences in composition.
Since these
carbonatesdissolve in acid, the persistence of these mounds indicates that water perhaps less
acidic and more
favorable for life might have once flowed across Mars.
More detailed analyses and searches for other signs will surely continue.